A standard coupling is used for feeding a heat-exchange medium, e.g. oil, to a rotating body or load such as a drying drum, heating roller or the like. The coupling is connected as described in U.S. Pat. No. 5,156,523 between a stationary supply of the medium and the rotating load and comprises a tubular rotor shaft fixed to the rotating load and rotatable about and centered on an axis and a nonrotatable support/housing fixed stationarily adjacent and surrounding the load. This support/housing is provided with an inlet connected to the supply and is formed with a passage permitting fluid communication between the supply and the load through the shaft. At least one roller bearing that is lubricated with grease or oil rotationally supports the shaft in the housing and outer and inner seals axially flanking the bearing define an annular substantially closed chamber containing the bearing and each seal between the housing and the shaft so that the oil lubricant is segregated from the heat-exchange medium. The inner seal has an inner side exposed to the medium and the outer seal has an outer side exposed to the surrounding atmosphere. A coolant is circulated through the chamber.
Thus the coolant lubricates the bearings. The cooled bearing therefore not only has an increased service life, but also any chemical reaction with the lubricant is ruled out. Furthermore the bearings do not have to be designed for very high temperatures and the heat expansion incurred thereby.
The described system is nonetheless fairly complex. Furthermore the circulating heat-exchange medium and the lubricant for the bearing can mix somewhat. What is more the bearing is often excessively heated by the hot heat-exchange medium, shortening the bearing service life.